Question

The sum of the digits of a 2-digit number is 9. The number obtained by subtracting 9 from the number is equal to four times the number obtained by reversing it's digit. Find the number?

answer = 81 ​

Answer 1

Answer:

Let the number be in the form of `10 x +y` , where x and y are the tens digit and the units digit respectively.

Applying the first condition given in the problem, we get `x +y =9 to (1)`

Applying the second condition givent the problem, we get

`10 x +y -9 = 10 y +x`

` x-y =1 to (2)`

Solving equations (1) and (2)

We get `x = 5 and y =4`

`therefore ` The number is 54.

Answer 2

Answer:

6x +6y -6x +39y = 45

45y = 45

y = 45/45

y = 1

Put y = 1 in e q 1

X+1 = 9

X = 9-1

x = 8

Therefore

Number

= 10(8)+1

= 80+1

= 81

• Answer: 81